Process for the manufacture of sodium sulphide



JuneY 2; 11.925. 1,540,711

- A. PRATT ET AL PROCESS FOR THE MANUFAGTURE OF SODlUM SULPHIDE FiledA1122. 5" 1922 Patented June f2, 1925.)

uNlTED STATES PATENT omer..

LTER ALBERT PRATT ANDJOHN H. CLARKE, OF WINCHESTER, MASSACHUSETTS,

ASSIGNORS T MERRIMAC. CHEMICAL COMPANY, OF WOBURN,

A CORPORATION 0F MASSACHUSETTS.

MASSACHUSETTS,

PROCESS FOR THE MANU'FACTURE OFSODIUM SULPHIDE.

Appumian mea August a, 1922. semi No. 57ans.

' 'To all whoml it may con/Jem.' Be it known that we, (1) LESTER ALBERTPRATT and (2) JOHN H. CLARKE, citizens of (1) the United States, (2)Canada, subject l of King of Great lBritain, residing at (1) Winchester,I (2) Winchester, in the county of (1) Middlesex, (2) Middlesex, andState of (1) Massachusetts, (2) Massachusetts,V

have invented certain new and useful Iml.' provements in Processes forthe Manufac` ture of Sodium Sulphide, of which the following is aspecification.

' This invention relates to a process for the manufacture of sodiumsulphide. 1,5 The principal object of the invention is to provide aneconomical and efficient process for the manufacture of sodium sulphide.Other objects of the invention, the accomplishment of which vcontributeto the acy, complishment of the principal object are to provide aprocessin whichthe reaction conditions, particularly the temperature,

,are subject to easy and accurate control;

the production of high yields of relatively pure product; the use ofinexpensive apparatus, that is, kapparatus for which the combinedoriginal cost and maintenance costfis low as compared with the value ofthe'product; economy of heat; small oxida- 00 ltion or lsecondarreaction losses; and small losses by volatilization. 4

Other objects 'and advantages of the ini vention will be apparent fromthe follow-- ing detailed description of the invention.

rlhe process consists in flowing fused sodium sulphate (salt cake) orsodium acid sulphate (niter cake) mixed with finely divided carbonaceousmaterial over or through a body yor mass of highly heatedl 40 inertmaterial.

The process preferably is carried out in an electrically heated shaftfurnace of either the resistance or induction type, butv I contemplatethe' use of any other method ofl heating which may be applied vwithoutcontacting the furnace chargewith air or products of combustion. Forinstance, a

shaft furnace containing a filling of inertv 0 .material through whichthe charge of salt 5,

1 opening 3.

-cake or niter cake and carbonaceous ma.-`

te-rial is flowed may be heated by a flame or b3' contact with a hotbody, such as a body of incandescent coke surrounding the shaft of thefurnace. It is therefore to be understood that the invention is notlimited to electrical 4heating excepting as is required by the appendedclaims. i

Apparatus suitable for carrying out the process is illustrated in theaccompanying drawing in which they figure is a vertical section of aninduction electric furnace.

Referring to the" drawing, 1 is the outer shell of the furnace formed ofearthenware, brick or other suitable structural material which is a poorconductor of heat and electricity. The shell 1 ...rests on a base v2which may be made of concrete, said base 2 having a discharge opening 3provided with a suitable closure re resented by the slide 4. The upperend o shell 1 is closed by a cover plate' 5 having a charge opening 6provided with a suitable closure represented by the slide 7 Extendingbetween the charge opening 6- and the discharge opening 3 is acylindrical shaft formed of suitable non-.conductin terial. vAs, isillustrate the lup er or pre-v heating zone 8 is formed o magnesiabrick; the central or reaction zone 9 is formed of carbon brick; and thelower or drawing olf zone 10 is formed `of magnesia brick. The Ainnerwalls of the zone 10 of the shaft slope inwardly to the discharge nacewhich compriseslthe furnacecharge and the carbon brickj walls of thereaction zone 9. The` coil 11 is cooled by means of water flowedAthrough it as indicated. y

'as magnesia brick. The filling 12 may be made up of regular orirregular forms or fragments of inert material.. In practice the unitsof the supporting and distribute `ing filling preferably presentsloping. surfaces to the owing charge. On the drawing the filling 12 isconventionally illustrated as checkerwork.

The process is carried out as follows:

`Electric current is supplied to the primary coil 11 sulicient to heatthe reaction zone 9 of the furnace to a 4temperature of from 850 to 1100C.; and a mixture of carbonaceous material crushed to at least 20 meshand ground salt cake or niter cake or a mixture of salt cake and nitercake is supplied to the furnace through the charge opening 6. Thecarbonaceous material employed in the charge preferably is free ornearly free from ash or other impurities. IPetroleum coke is asatisfactor carbonaceous material. The proportions o carbonaceousmaterial and salt cake or niter cake in the charge may vary. Goodresults are obtained by chargingthe furnace with a mixture of 12 parts`by weight of salt cake with' 5 parts by weight of petroleum coke. Withthis mixture and by maintaining a temperature in the reaction zone. ofthe furnace between through the charge opening 6 is preheated inthe zone8 and arrives at the filling of inert material 12 )in the reaction zone9 in yiso molten and iuent-condition. The molten material flows in thinlayers over the surfaces of the inert filling and due to the lar esurface exposure rapid conversion of t e sulphate to sulphide takesplace. The molten reaction product collects in the drawing -ol zone 10and is withdrawn fromtime to 4on the drawing.

' If crystallized sodium sul hide is` desired the furnace product isdisc ar directly into water in 'a saturated so u tion o the sodiumsulphide Acontent of the furnace product. The bulk ofthe unccnvertedsodium sulphateremains in the undimlolved residue and after separa-`returned to the process.

phide solution isseparated from the iindissolved residue by filtrationorA settling and'- uantity. 'ust su'cient to form. l 'inert materlal atcause such material does not introduce impurities into the product.Otherwise if impure carbonaceous material is used, such as coke fromcoal containing large amounts of ash, collodial or gelatinous silicatesof iron and aluminum will be formed when the furnace product is treatedwith water and interfere with the settling or filtration operation inthe separation of the solution of sodium sulphide from the undissolvedresidue.

As is indicated above the sodium sulphate for the reaction is derivedfrom either salt cake or niter cake or mixtures thereof and it is to beunderstood that these materials or any other sodium sulphate containingmaterials are included under the expression sodium sulphate in theappended'claims.

We claim:

l. Process for the manufacture of sodium sulphide which comprises`flowing a mixture of molten sodium sulphate with nely dividedcarbonaceous material in quantity suflicient to reduce `thesulphate tosulphide through a supporting and distributing body of inert material atreacting temperature.

2. Process for the manufacture'of sodium sulphide which comprises,mixing material containing sodium sulphate with finely dividedcarbonaceous material in quantity sufficient to reduce the sul hate tosulphide, melting the mixture, 'and lbwing the melted mixture downwardlythrough a column of inert material at reacting temperature.

,/3. Process for the manufacture of sodium sulphideV which comprisesheating to reacting temperatures. molten mixture of sodium sulphate with'finely divided carbonaceous material in quantity sufficient to reducethe sulphate to sulphide in a thin layer in contact'with inert material.

4. Process for the manufacture of sodium sulphide which comprisesflowing a molten vlll) mixture of. sodium sulphate with finely dividedfcarbonaceous' material in quantity sufficient to reduce the sulphate tosul hideover a supporting and distributin b yof to 1100 C.

5. Process for theimannfa'ctur'e of sodiumY sulphide which comprises,mixing about 12 tion from the sodium sul hide solution is -parts ofcrushed salt cake with about 5 e sodiuk -sulof pulverized'y partstroleum coke, melting the mixture, and owingthe molten mixturedownwardlly throughs. column of inert maa temperatureof rom 850 terialheated to a temperature of from 850 of inert material, and passingelectric curto 950 C. rent through the flowing molten mixture to 10 6.Process for the manufacture of sodium heat the same to reactingtemperature.

sulphide which comprises, flowing a molten In testimony whereof7 weaflix our Signamixture of sodium sulphate With finely ditures. videdcarbonaceous material in quantity suicient to reduce the sulphate t0sulphide LESTER ALBERT PRATT.. through a supporting and distributingbody JOHN H. CLARKE.

